Many repository concepts rely, among other things, on the use of geotechnical barriers based on bentonite. Its geochemical properties as well as a compaction at re-saturation by the resulting swelling pressures and thus the closing transport pathways are the functional basis of the suitability of this material. Numerical simulations of the multiphysical processes are a valuable tool for the design and performance assessment of bentonite barriers.

In this project, process and constitutive models for bentonite barriers are developed, implemented and verified in the open-source software OpenGeoSys. Special consideration is given to the inelastic behaviour of the bentonite, hydraulic and mechanical anisotropies as well as the swelling and shrinkage behaviour coupled to changes in water content.

The foundation of the model are balance relations derived from the theory of porous media which consider the compressibility of the solid and fluid phases. Due to the strong nonlinearities, especially of the constitutive relationships used for the two-phase flow and the deformation behaviour, time-adaptive methods are used for the numerical simulations.

 The project is funded by the Federal Institute for Geosciences and Natural Resources in Hannover.